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A137230 Numbers that are divisible by the number of their prime factors (excluding primes). 2
4, 6, 10, 12, 14, 16, 18, 22, 24, 26, 27, 30, 34, 36, 38, 40, 42, 45, 46, 56, 58, 60, 62, 63, 66, 74, 75, 78, 80, 82, 84, 86, 88, 94, 96, 99, 100, 102, 104, 105, 106, 114, 117, 118, 120, 122, 132, 134, 136, 138, 140, 142, 144, 146, 147, 152, 153, 156, 158, 165, 166 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence (S) is defined by n in S <--> {mod[n,r(n)] = 0 & n NOT prime}. r(n) is equivalent to BigOmega(n). This sequence is obtained from A074946 by excluding all primes within that sequence.

LINKS

Table of n, a(n) for n=1..61.

Eric Weisstein's MathWorld Prime Factor

EXAMPLE

n = 3; not in S because does not satisfy "n NOT prime."

n = 4; in S because satisfies both mod[n,r(n)] = 0 and n NOT prime.

MATHEMATICA

Select[Range[200], CompositeQ[#] && Divisible[#, PrimeOmega[#]]&] (* Jean-Fran├žois Alcover, Nov 11 2016 *)

CROSSREFS

Cf. A074946.

Sequence in context: A287342 A163164 A120351 * A283564 A181794 A199536

Adjacent sequences:  A137227 A137228 A137229 * A137231 A137232 A137233

KEYWORD

nonn

AUTHOR

William A. Tedeschi, Mar 07 2008

STATUS

approved

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Last modified June 16 12:38 EDT 2019. Contains 324152 sequences. (Running on oeis4.)